Lens system for measuring the refraction of the eye.



giga i lll z .UNITED sTATEs n PATENT oEEioE.

HENRY L. DE ZENG, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THE DEZENG-- STANDARD COMPANY, A (.fORIO/RATION OF NEW JERSEY.

LENS SYSTEM FOR MEASURINGA THE REFRACTION OF THE EYE.

Specification of Letters Patent.

Patented May 5, 1908.

Application filed December 31. 1906. Serial No. 350.291.

TocZZ 'whom it may concern:

.Be it known that I, HENRY L. DE ZENG, a citizen of the United States,residing' in the city andl county of Philadelphia, State ofPennsylvania, have invented a new and useful Lens System for Measuringthe Refraction of the Eye, of which the following is a specification. l

My .invention consists of a lens system for measuring the differentmeridians of the eye embodying a plurality of rotatable lensespossessing unequal refraction in their different meridia-ns, means forrotating said lenses with respect to each other about a common center,means for recording the various 01ptical values produced by the rotationof t ie said lenses and means for locating the cylindrical axesresultant from said lens combination, the device being adaptable to thecell of an optical trial frame or some other suitable holder providedwith a Vernier graduated iii degrees and also provided with meanspermitting the rotation of the deviceI intact about ageometrical center.

Figure 1 represents a face view of a rotary lens system for eye testingembodying my invention. Fig. 2 represents a section. thereof on line-ci., Fig. 1. Fig. 3 represents a side elevation of one of the lensesemployed. Fig. 4 represents a section of said lens at a right angle tothat shown in Fig. 2. Fig. 5 represents a face view of another form ofthe device embodying my invention. resents a section on line Iy-y, Fig.5. Fig. 7 represents a section of a portion on line z-e, Fig. 6. Fig. 8represents a side elevation of one of the lenses employed. Fig. 9represents a section thereof on line o o', Fig. S.

Similar letters of reference indicate corresponding parts in thefigures.

Referring to the drawings: Ailesigiiates a casing within which aremounted the lenses B and the saine being respectivelyplanof conveXandplano-concave cylinders, the rim of each of said lenses having thereon,a circular rack D, with which meshes the pinion E whose shaft isconnected with the stein F whereby by operating the latter, rotation isimparted to the lenses B and C in reverse order, said stem in thepresent instance, proj ecting radially from the casing A.

Connected with the rim of the lens B is the scale G, the same appearingat the front of the casing A, and connected with the rim of the lens Cis the index H, which projects foi'- Fig. 6 repy larly hereinafterreferred to.

wardly from said rim through a chamber in said casing and occupies aposition adjacent to the peri hery of the scale G so as to point to thegrarfiiations thereof. i

On the face of the casing A are the characters and the words Axis7 andthe meridian marks as at G for locating the-optical aXes of thecombination as more particu- On the periphery of the casing A is theannular flange A', which projects radially therefrom beyond the same. Bythis provision, the device is adapted to be used in the cell of aregular dculists trial frame or other suitable lio dei', arid permittedto be revolved therein for the purpose of locating the required positionof the cylindrical axis before the eye.

the reverse rotation of the lenses, the same embodying a lurality ofpinions J which mesh with eac i and with the racks on the rims of thelenses, the shafts of said pinions being mounted on the casing A, one ofthe saine being connected with the stein K, the latter projectingoutwardly from the side of the casing, the operation, however, being thesaine as that roduced by the mechanism shown in the ot ier 'figuresrespect to'eacli other iii reverse oi'dei about a common center, producea variety of foci inA the following'manner: -As there are four dif;ferent forms of lenses eiwnployfedfi"thefiiieasurenient 4and correbtinof astigmatism of the eye all of which possess` une( ual retractionIiiiftlieiijfrliiferent incridiaiis, lknown as the plano-cylinder, thesphero-cylinder, the cross cylinder and the torio-cylinder, any of whichup with the plano-cylinders.

cave "cy inder ofthe initial power say of four dio ters each so mountedin the double rotatablel cell, that when their axes are parallel, andthey are consequently neutral, the pointer registers zero on the scale.By rotating them in opposite directions, and thus separating their axes,a positive quantit Y is obtained in one meridian, and a nega livequantity of equal amount is obtained in the iiieridianat a right anglethereto. The rota- 'tion of the lenses, therefore, from that point atwhich their axes are parallel to a point at In Fig. 5, I show anotherform of effecting Vl might use with equal results, I liavffr simplicitysSake, shown my invention made I eingloy a plano-convex and a plaiio-con-'llhglenses possessing une ual refraction in their diflerentiiieiidians, wil if rotated with los f which their axes are at a rightangle with one zero to ourdiopters in the meridian at a' right anglethereto as indicated by the minus and pl-us meridian axis marks. A

As one meridian of the lens system represents a positive, andthe othermeridian at a right angle thereto a negative quantity at all timesexceptinguwhen the axeswofmthecylin; ders are parallel,theec'gfiiivalenttoa yariety Qileriss iiiibofth'plus'and minuscan beobtained and'iecorded upon themscaleby'theide grefeibf rotationofthesaidM lenses. It will thus be seen Vthat my invention obviates thenecessity of employing alarge variety oflenses and their frequentinterchange when rnveasuroieg tllety@ ffrastgmatism and Other .errors-Having thus described my-,invention, what lI claim as new and desire tosecure by Letters Patent, iszi 1. The combination of a plurality oflenses possessing the physical qualities of a cylinder, 'means forreversely rotating said lenses with respect to each other about a commoncenter, means for recordin the various focal iquivalents produced by t erotation of said lenses, means for locating the cylindrical axis of thesaid lens combination, and a spaced body having an outwardly extendingportion v to hold the same in a trial frame or other suitable holder.

2. The combination of a plurality of lenses possessing the physicalqualities of a cylinder, means for reversely rotating said lenses withrespect to each other about a common center, means for recording thevarious focal equivalents produced by the rotation of said lenses, meansfor locating the cylindrical axis resultant from said lens combination,and a spaced body having an outwardly extendin1 circular portion to holdthe same in a trial` frame or other suitable holder and permits therotation of the device geometrical center.

Witnesses:y f

JOHN A. WIEDERSHEIM, f WM. C. VIEDERSEIM.

intact. about a HENRY L. DE ZENG.

